Methods and storage media for dimming a display screen

ABSTRACT

A method includes acquiring a parameter value of a display screen to be adjusted; comparing the parameter value to a first set threshold and a second set threshold less than the first set threshold respectively. When the parameter value is equal to or greater than the first set threshold, perform dimming on the display screen, under a one-pulse condition, via both emission dimming mode and source dimming mode, or source dimming mode, to adjust the duty ratio of PWM to a first duty ratio. When the parameter value is less than the first set threshold, and is equal to or greater than the second set threshold, perform dimming on the display screen, under a multi-pulse condition, via both emission dimming mode and source dimming mode, or source dimming mode, to adjust the duty ratio of PWM to a second duty ratio less than the first duty ratio.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/328,735 filed on Feb. 27, 2019, which is a 35 USC § 371 U.S. nationalstage filing of International Patent Application No. PCT/CN2018/086764filed on May 14, 2018, and claiming priority under the Paris Conventionto Chinese Patent Application No. CN 201710524423.7 filed on Jun. 30,2017, all of which are incorporated herein by reference for all thatthey teach and disclose without exclusion of any portion thereof.

TECHNICAL FIELD

The present disclosure relates to the technology field of display, andmore particularly, to methods, and storage media for dimming a displayscreen.

BACKGROUND

In some specific application fields (e.g., display screens for cockpits,aeronautical equipment, handheld devices and the like), display screensare desired to have a good dimming performance, so as to be able to bewatched comfortably either in daytime or at night. However, since thetraditional dimming technologies may reduce the display quality duringthe process of dimming, the problem that how to mitigate impacts on thedisplay quality while dimming is very desired to be solved.

SUMMARY

In view of above, it is needed to provide methods and storage media fordimming a display screen in regard with the problem that how to mitigateimpacts on the display quality while dimming

Provided is a method for dimming a display screen, including: acquiringa parameter value of the display screen to be adjusted, the parametervalue corresponding to a brightness of the display screen; comparing theparameter value to a first set threshold and a second set thresholdrespectively; when the parameter value is equal to or greater than thefirst set threshold, entering a first phase, and performing dimming onthe display screen, under a one-pulse condition, via both emissiondimming mode and source dimming mode, or source dimming mode, to adjustduty ratio of PWM (Pulse Width Modulation) to a first duty ratio,wherein the duty ratio of PWM refers to a ratio of efficiency level in aframe to be displayed by the display screen; when the parameter value isless than the first set threshold, and is equal to or greater than thesecond set threshold, entering a second phase, and performing dimming onthe display screen, under a multi-pulse condition, via both emissiondimming mode and source dimming mode, or source dimming mode, to adjustduty ratio of PWM to a second duty ratio; and when the parameter valueis less than the second set threshold, entering a third phase, andperforming dimming on the display screen, under another multi-pulsecondition, via emission dimming mode, to adjust duty ratio of PWM to athird duty ratio, wherein the second set threshold is less than thefirst set threshold, and the second duty ratio is less than the firstduty ratio, the third duty ratio is less than the second duty ratio.

Under the multi-pulse condition, the duty ratio of PWM is changed one byone in sequence, along with sequentially happenings of pulses in themulti-pulse condition. By such a dimming method, the brightness can beadjusted into more accurate volume. It would be more stable to emitlight.

After acquiring a parameter value of the display screen to be adjusted,the parameter value will be compared with a set threshold to obtain acomparison result, and a corresponding dimming mode will be determinedaccording to the comparison result to perform dimming on the displayscreen according to the method, apparatus, storage medium and electronicdevice for dimming a display screen as described above. Since variousdimming modes have different performances with different brightnesses,if only one dimming mode is determined for dimming, the display qualitymay be reduced with the brightness with which the one dimming mode doesnot perform good. Therefore, the above method for dimming a displayscreen that determines a dimming mode according to a comparison resultmay overcome the deficiency caused by determining only one dimming mode,and may further mitigate impacts on the display quality while dimming

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the technical solutions of theembodiments of the present disclosure or of the prior art moreexplicitly, the accompanying drawings to be used necessarily for thedescription of the embodiments or the prior art will be brieflydescribed below. Apparently, the accompanying drawings described beloware part of the embodiments of the disclosure only, and accompanyingdrawings of the other embodiments may further be acquired based on theseaccompanying drawings herein without creative efforts to those ofordinary skill in the art.

FIG. 1 is a flow diagram of the method for dimming a display screenprovided by an implementation.

FIG. 2 is a specific flow diagram of one of the embodiments of themethod for dimming a display screen of the implementation shown in FIG.1.

FIG. 3 is a circuit diagram of one of the embodiments of the pixeldriving module involved in the implementation shown in FIG. 1.

FIG. 4 is a flow diagram of another embodiment of the method for dimminga display screen of the implementation shown in FIG. 1.

FIG. 5 is a block diagram of the apparatus for dimming a display screenprovided in another implementation.

FIG. 6 shows a duty ratio of PWM changes along with sequentiallyhappenings of pulses in the multi-pulse condition.

DETAILED DESCRIPTION OF THE EMBODIMENTS

To facilitate understanding the present disclosure, it will be describedhereinafter more thoroughly in reference with the relative accompanyingdrawings. The preferred embodiments of the present disclosure areprovided in the accompanying drawings. However, the present disclosuremay be implemented in various forms, and not limited in the embodimentsdescribed herein. In contrast, the objective of providing theseembodiments is to understand the disclosed description of the presentdisclosure more thoroughly.

All technical and scientific terms as used herein have the same meaningas commonly understood by those skilled in the art, unless those definedotherwise in context. The terms as used herein in the description of thepresent disclosure are for the purpose of describing particularembodiments only, and are not intended to be limiting of the presentdisclosure. The term “and/or” as used herein includes arbitrary and allcombinations of one or more of the associated listed items.

One implementation provides a method for dimming a display screen, whichmay be performed by a peripheral drive chip for controlling the displayscreen. Specifically, the display screen may drive a pixel by athin-film transistor. Specifically, the display screen, for example,includes a pixel matrix, a row driving module and a column drivingmodule. The pixel matrix includes a plurality of pixel driving modulesand a plurality of pixels, each of which is controlled by one of thepixel driving modules. The row driving module sends a scanning signal toeach of the pixel driving modules via a row (scanning) address bus. Thecolumn driving module sends a data signal to each of the pixel drivingmodules via a column (data) address bus. The peripheral drive chip,which is responsible for processing and transmitting data, sendingcontrol signals and the like functions of the whole display screen, iselectrically connected to the row driving module and the column drivingmodule respectively. The peripheral drive chip is consisted of, e.g., asingle-chip microcomputer (or FPGA) and a peripheral module.

In reference with FIG. 1, the method for dimming a display screenprovided in the present implementation includes the following steps.

At step S100, a parameter value of the display screen to be adjusted isacquired. In such a context, the parameter value has a correspondencewith a brightness of the display screen.

In such a context, the parameter value of the display screen to beadjusted implies that it is expected to adjust the parameter of thedisplay screen to the parameter value. The fact that the parameter valuehas a correspondence with a brightness of the display screen impliesthat the parameter value will change in turn if the brightness ischanging The parameter value is for example a brightness value, avoltage value, a current value, or a gray scale. The parameter value maybe set by a user via an interactive interface of the device providedwith the display screen, and the parameter value set by the user is sentto the peripheral drive chip by the CPU of the device after the usersetting is accomplished. Alternatively, the parameter value to beadjusted may also be generated automatically by the CPU or theperipheral drive chip (i.e., having an automatic dimming functionality).For example, it is assumed that the parameter value is a brightnessvalue, it is possible then to provide a light sensor configured todetect an external light intensity. The CPU or the peripheral drive chipgenerates a brightness value suitable for the user to watch according tothe light intensity value detected by the light sensor, and thisbrightness value serves as the brightness value to be adjusted.

At step S200, the parameter value is compared with a set threshold toobtain a comparison result, and a corresponding dimming mode isdetermined according to the comparison result to perform dimming on thedisplay screen.

At this step, a different dimming mode may be determined when thecomparison result is different. For example, when the parameter valuesfalls within different ranges, a dimming mode having a better dimmingperformance than that within the other ranges is determined to performthe dimming By way of example, it is assumed that the impact of thefirst dimming mode on the display quality with a parameter value withina first range is less than the impact of the first dimming mode on thedisplay quality with a parameter value within a second range, while theimpact of the second dimming mode on the display quality with theparameter value within the second range described above is less than theimpact of the second dimming mode on the display quality with theparameter value within the first range described above. Thereby, if itis determined that a parameter value falls in the first range, the firstdimming mode described above is then used to perform dimming, while ifit is determined that the parameter value falls in the second range, thesecond dimming mode is then used to perform dimming, so that the displayquality can be improved while dimming.

Since various dimming modes have different performances with differentbrightnesses, if only one dimming mode is determined for dimming, thedisplay quality may be reduced with the brightness with which the onedimming mode does not perform good. Therefore, the above method fordimming a display screen that determines a dimming mode according to acomparison result may overcome the deficiency caused by determining onlyone dimming mode, and may further mitigate impacts on the displayquality while dimming

In one of the embodiments, the display screen described above drives apixel by a thin-film transistor (TFT). Furthermore, the step S200 asdescribed above includes the following steps in reference with FIG. 2.

At step S210, a first dimming mode is adopted to perform the dimming onthe display screen when it is determined that the brightnesscorresponding to the parameter value is less than the set threshold. Avoltage of a data signal received by a pixel driving module in thedisplay screen is not changed during a process of the dimming in thefirst dimming mode.

In such a context, the set threshold is for example between 70 nits and90 nits. Optionally, the set threshold is 80 nits. One of the pixeldriving modules is shown as in FIG. 3. In this pixel driving module,included are a TFT T1, a TFT T2, a TFT T3, a capacitor C1 and a pixelD1. In such a context, a gate and a drain of the TFT T1 are connectedrespectively to the row address bus and the column address bus.Furthermore, the signals received by the gate and the drain of the TFTT1 correspond to the scanning signal (Vscan) and the data signal(Vdata). In the embodiment shown in FIG. 3, thus the voltage of the datasignal received by the drain of the TFT T1 is not changed during theprocess of the dimming, but the dimming is performed by changing inputsignals from other devices in the pixel driving module in the firstdimming mode.

If the dimming is performed by changing the voltage of the data signalduring the process of the dimming, the lower the brightness value to beadjusted is, the higher the voltage of the data signal is required tobe. In such a context, it will increase the difference incharacteristics of the TFTs, resulting in occurring the phenomenon ofuneven brightness in the row direction of the screen. In thisembodiment, thus when the brightness corresponding to the parametervalue to be adjusted is less than the set threshold, the adopted firstdimming mode then performs the dimming not by changing the voltage ofthe data signal, but in other manners, so as to avoid occurring thephenomenon of uneven brightness in the row direction of the screenresulted from the increase of the difference in characteristics of theTFTs.

In one of the embodiments, the step S200 further includes adopting thesecond dimming mode, when it is determined that the parameter value isnot less than the set threshold. In such a context, the step S200described above specifically includes the following steps in combinationwith the step S210 of the embodiment in reference with FIG. 4 asdescribed above.

At step S211, it is determined whether the brightness corresponding tothe parameter value is less than the set threshold. If it is positive,the step S212 is performed. If it is negative, the step S213 isperformed.

At step S212, the first dimming mode is adopted.

At step S213, the second dimming mode is adopted. In such a context, thedimming is performed by adjusting the voltage of the data signal in thesecond dimming mode.

In this embodiment, thus when it is desired to be adjusted to a highbrightness or a low brightness, different dimming modes are adoptedrespectively, i.e., the second dimming mode is adopted when it isdesired to be adjusted to the high brightness, and the first dimmingmode is adopted when it is desired to be adjusted to the low brightness.

In such a context, the second dimming mode is for example a sourcedimming mode. As shown in FIG. 3, the expression of current of the pixelD1 is

I _(oled) =k(VDD−Vdata)²   (1),

wherein I_(oled) is the current of the pixel D1, and k is a coefficient.As known from the formula (1), since the voltage between the powersupply VDD and the data signal (Vdata) plays a decisive role to thecurrent of the pixel D1, adjusting the data signal (Vdata) meansadjusting the current of the pixel D1 while on the premise that thepower supply VDD is unchanged, so as to achieve brightness adjustment.If it is desired to adjust the brightness to be higher, it is requiredthen to reduce the voltage of the data signal (Vdata) If it is desiredto adjust the brightness to be lower, it is required then to increasethe voltage of the data signal (Vdata).

In view of this, it is required to reduce the voltage of the data signal(Vdata) when it is desired to adjust the brightness to be higher inrespect with the second dimming mode. When the voltage of the datasignal (Vdata) is sufficiently low, the difference in characteristics ofthe TFTs is small enough to be ignored. It is required to increase thevoltage of the data signal (Vdata) when it is desired to adjust thebrightness to be lower, and the lower the brightness value to beadjusted, the higher the voltage of the data signal (Vdata) is required.When the data signal (Vdata) is sufficiently high, the difference incharacteristics of the TFTs is so large that the phenomenon of unevenbrightness in the row direction of the screen and color spots may occur.Therefore, if continuing to adopt the second dimming mode when it isdesired to adjust the brightness lower, the display quality will beaffected. In view of the situations described above, if it is desired toadjust the brightness corresponding to the parameter value to be lowerthan the set threshold in this embodiment, the second dimming mode isswitched to the first dimming mode, so as to avoid the phenomenon ofuneven brightness in the row direction.

Specifically, the dimming is performed by adjusting the illuminationperiod of the pixel in each frame in the first dimming mode. Optionally,the first dimming mode is an EM (Emission) dimming mode. In such acontext, the brightness of the pixel may be reduced by reducing theillumination period of each frame. For example, if the PWM (Pulse WidthModulation) signal is used to control the illumination period of thepixel, the illumination period of each frame may be then reduced byreducing the duty ratio of an active level (e.g., a low level) in thePWM signal, so as to reduce the brightness of the pixel. In such acontext, the pixel illuminates only with the active level.

The working principle of the first dimming mode described above will bethen illustrated in reference with FIG. 3 as an example. If the firstdimming mode is adopted, it is only required to adjust the duty ratio ofthe Vpwm signal applied to the gate of the TFT T3, but without changingthe data signal (Vdata), to change the illumination period of the pixelD1 in each frame, such that the brightness of the pixel D1 may beadjusted.

Furthermore, if the dimming is performed by adjusting the duty ratio ofthe PWM in the first dimming mode, the dimming frequency is then fixed,where the phenomenon of photo screen rolling may occur under highbrightness conditions. In this embodiment, thus if the parameter valueto be adjusted is higher than the set threshold, the second dimming modeis adopted so as to avoid occurring the deficiency of the photo screenrolling described above, which further improves the display quality.

In a specific embodiment, the dimming process includes following phases.

A parameter value of the display screen to be adjusted is acquired, theparameter value corresponding to a brightness of the display screen.

The parameter value is compared to a first set threshold and a secondset threshold respectively.

When the parameter value is equal to or greater than the first setthreshold, it is in a first phase. In the first phase, the dimmingprocess includes performing dimming on the display screen, via bothemission dimming mode and source dimming mode, or the source dimmingmode, under a one-pulse condition, to adjust duty ratio of PWM (PulseWidth Modulation) to a first duty ratio.

When the parameter value is less than the first set threshold, and isequal to or greater than the second set threshold, it is in a secondphase. In the second phase, the dimming process includes performingdimming on the display screen, via both emission dimming mode and sourcedimming mode, or the source dimming mode, under a multi-pulse condition,to adjust the duty ratio of PWM to a second duty ratio.

The second set threshold is less than the first set threshold, and thesecond duty ratio is less than the first duty ratio. In the secondphase, as shown in FIG. 6, the duty ratio of PWM under the multi-pulsecondition is changed one by one in sequence, along with sequentiallyhappenings of pulses in the multi-pulse condition.

When the parameter value is less than the second set threshold, it is ina third phase. In the third phase, the dimming process includesperforming dimming on the display screen via the emission dimming mode,under another multi-pulse condition, to adjust the duty ratio of PWM toa third duty ratio less than the second duty ratio. In the third phase,as shown in FIG. 6, the duty ratio of PWM under the another multi-pulsecondition is changed one by one in sequence, along with sequentiallyhappenings of pulses in the another multi-pulse condition.

Under the multi-pulse condition, the duty ratio of PWM is changed one byone in sequence, along with sequentially happenings of pulses in themulti-pulse condition. By such dimming process, the brightness can beadjusted into more accurate volume. It would be more stable to emitlight.

Optionally, the first set threshold ranges between 350 nits and 380nits, and the second set threshold ranges between 200 nits and 240 nits.

Optionally, the first duty ratio is greater than 90%, and the secondduty ratio is greater than 80%.

Optionally, the third duty ratio ranges between substantially 1% andsubstantially 88%.

Under the above volume condition, display uniformity can be improved,and brightness can be adjusted to a suitable state. The quality ofdisplaying can be improved.

The duty ratio of PWM refers to a ratio of efficiency level in a frameto be displayed by the display screen. The display screen emits underthe efficiency level. The efficiency level can be low level, or highlevel.

In the emission dimming mode, brightness is adjusted by adjusting theduty ratio of PWM.

In the source dimming mode, brightness is adjusted by adjusting datavoltage.

Multi-pulse in the above multi-pulse condition refers to four pulses,eight pulses, sixteen pulses, or other integral multiples of four pulseshappened in a frame.

It is to be illustrated that FIG. 1, FIG. 2 and FIG. 4 are the flowschematic diagrams of the method of the embodiments of the presentdisclosure. It should be understood that although all of the steps inthe flow diagrams of FIG. 1, FIG. 2 and FIG. 4 are shown sequentially asthe indication of the arrows, these steps do not have to be performed insuch sequence as indicated by the arrows. Performing these steps doesnot have any sequential limitation such that these steps may beperformed in another sequence, unless it is illustrated explicitly inthe context. Further, at least a part of steps of FIG. 1, FIG. 2 andFIG. 4 may include multiple sub-steps or stages which may be performedat different times rather have to be accomplished at the same time,which may be performed in turn or alternately with the other steps or atleast a part of the sub-steps or stages of the other steps, rather haveto be performed sequentially.

In another implementation, provided is an apparatus for dimming adisplay screen in reference with FIG. 4, which includes the belowcomponents.

A parameter value acquisition module 110, or can be called intoparameter value acquisition module, is configured to acquire a parametervalue of the display screen to be adjusted. In such a context, theparameter value has a correspondence with a brightness of the displayscreen.

A dimming determination module 120, or can be called into dimmingselection module 120, is configured to compare the parameter value witha set threshold to obtain a comparison result, and to determine acorresponding dimming mode according to the comparison result to performdimming on the display screen.

In one of the embodiments, the display screen drives a pixel by athin-film transistor.

Furthermore, the dimming determination module 120 includes the followingelements.

A first dimming determination module, configured to adopt a firstdimming mode to perform the dimming on the display screen when it isdetermined that the brightness corresponding to the parameter value isless than the set threshold. A voltage of a data signal received by apixel driving module in the display screen is not changed during aprocess of the dimming in the first dimming mode.

In one of the embodiments, the dimming determination module 120 furtherincludes:

a second dimming determination module, configured to adopt the seconddimming mode when it is determined that the parameter value is not lessthan the set threshold. The dimming is performed by adjusting thevoltage of the data signal in the second dimming mode.

In one of the embodiments, the dimming is performed by adjusting anillumination period of a pixel of the display screen in each frame inthe first dimming mode.

In one of the embodiments, the parameter value is a brightness value.

In one of the embodiments, the set threshold is between 1 nit and 500nits.

It should be illustrated that the apparatus for dimming a display screenprovided in this implementation corresponds to the method for dimming adisplay screen of the implementation described above, thus it will notbe described repeatedly here.

In a further implementation, provided is a storage medium. The storagemedium may be a magnetic disk, an optical disk, a Read-Only Memory(ROM), or the like. The storage medium stores a program operable to beexecuted by a processor to perform the following steps of:

acquiring a parameter value of the display screen to be adjusted,wherein the parameter value has a correspondence with a brightness ofthe display screen; and

comparing the parameter value with a set threshold to obtain acomparison result, and determining a corresponding dimming modeaccording to the comparison result, and performing dimming on thedisplay screen.

It is to be illustrated that the steps performed by the processor inthis implementation correspond to the method for dimming a displayscreen of the implementation described above, thus they will not bedescribed here repeatedly.

In a still further implementation, provided is an electronic device,such as a mobile phone, computer or the like. The electronic deviceincludes a peripheral drive chip and a display screen. The peripheraldrive chip includes a processor and a memory storing a program operableto be executed by a processor to cause the processor to perform thefollowing steps of:

acquiring a parameter value of the display screen to be adjusted,wherein the parameter value has a correspondence with a brightness ofthe display screen; and

comparing the parameter value with a set threshold to obtain acomparison result, and determining a corresponding dimming modeaccording to the comparison result, and performing dimming on thedisplay screen.

It is to be illustrated that the steps performed by the processor inthis implementation correspond to the method for dimming a displayscreen of the implementation described above, thus they will not bedescribed here repeatedly.

All of the technical features in the embodiments described above can beemployed in arbitrary combinations. For purpose of simplifying thedescription, not all arbitrary combinations of the technical features inthe embodiments described above are described. However, as long as suchcombinations of the technical features are not contradictory, theyshould be considered as within the scope of the disclosure in thespecification.

The above embodiments are merely illustrative of several implementationsof the disclosure, and the description thereof is more specific anddetailed, but should not be deemed as limitations to the scope of thepresent disclosure. It should be noted that variations and improvementswill become apparent to those skilled in the art to which the presentdisclosure pertains without departing from its scope. Therefore, thescope of the present disclosure is defined by the appended claims

What is claimed is:
 1. A method for dimming a display screen,comprising: acquiring a parameter value of the display screen to beadjusted, the parameter value corresponding to a brightness of thedisplay screen; comparing the parameter value to a first set thresholdand a second set threshold respectively; when the parameter value isequal to or greater than the first set threshold, entering a firstphase, and performing dimming on the display screen, under a one-pulsecondition, via both emission dimming mode and source dimming mode, orthe source dimming mode, to adjust duty ratio of PWM (Pulse WidthModulation) to a first duty ratio; and when the parameter value is lessthan the first set threshold, and is equal to or greater than the secondset threshold, entering a second phase, and performing dimming on thedisplay screen, under a multi-pulse condition, via both emission dimmingmode and source dimming mode, or the source dimming mode, to adjust theduty ratio of PWM to a second duty ratio, wherein the second setthreshold is less than the first set threshold, and the second dutyratio is less than the first duty ratio.
 2. The method of claim 1,wherein in the second phase, the duty ratio of PWM under the multi-pulsecondition is changed one by one in sequence, along with sequentiallyhappenings of pulses in the multi-pulse condition.
 3. The method ofclaim 1, wherein the first set threshold ranges between 350 nits and 380nits.
 4. The method of claim 3, wherein and the second set thresholdranges between 200 nits and 240 nits.
 5. The method of claim 1, whereinthe first duty ratio is greater than 90%.
 6. The method of claim 5,wherein the second duty ratio is greater than 80%.
 7. The method ofclaim 1, when the parameter value is less than the second set threshold,entering a third phase, and performing dimming on the display screen,under another multi-pulse condition, via the emission dimming mode, toadjust the duty ratio of PWM to a third duty ratio, wherein the thirdduty ratio is less than the second duty ratio.
 8. The method of claim 7,wherein in the third phase, the duty ratio of PWM under the anothermulti-pulse condition is changed one by one in sequence, along withhappening of every pulse in the another multi-pulse condition.
 9. Themethod of claim 8, wherein the third duty ratio ranges betweensubstantially 1% and substantially 88%.
 10. The method of claim 1,wherein the duty ratio of PWM refers to a ratio of efficiency level in aframe to be displayed by the display screen.
 11. The method of claim 10,wherein the efficiency level in a frame is a low efficiency, or a highefficiency.
 12. A storage medium storing a program operable to beexecuted by a processor to make the processor perform the method ofclaim 1.